596 RAPID POPULATION GROW! words, working class women had 50 percent more children than middle upper class women (24, p. 207). Thompson and Lewis, surveying studi the United States, England and Wales, France, Germany, and Sweden, eluded that the middle and upper classes generally have fewer children the working class; that among farmers and workers, the least skilled and 1 with the lowest income have the largest number of children; and that th educated have more children than those with more education. The data England also show that the gap in fertility rates had been growing durin previous 50 years; that is, the upper and middle classes had begun to family size earlier than had the working class. We can hypothesize, there that family planning movements grow after the middle and upper cl lower their fertility but before the working classes have begun to do so. As a second example, the opposition of many non-Catholics in the U: States to the Catholic position on birth control stems not only fr( concern over the effect of Catholic views on public policy, but alsobecai is a factor in the higher fertility rates among Catholics. According to Kirk Catholic birth rate per 1,000 in 1952 was 36 compared to 25 non-Catholics. Though Catholics constituted only 20 percent of childbcaring segment of the total population, 30 percent of total births Catholic. Kirk also reported that in 1953, 70 percent of the Cat population was under 35 years of age compared to 57.5 percent of the c U.S. population under 35 (49). The differential fertility rate has led critics of the Catholic position to argue that "the effect of the oi Catholic position against birth control is to increase slowly but steadil ratio of Catholics to non-Catholics in this country" (50). It is also of political importance to note that the proportion of Catl in many American cities has been increasing. This is a reflection of the h birth rate among Catholics and a higher rate of migration of Protestar the suburbs. The result is that many American inner cities have high Cat as well as high Negro, populations. If the backlash voting in the inner i particularly as reflected in the high vote for Governor Wallace in the elections, is so heavily Catholic, this simply reflects the fact that Cat! constitute a substantial portion of the inner city. The high fertility rate among Negroes in the United States is also v: with some concern by many public figures and by some demographers, present trend continues, it is estimated that there will be over 50 n: mmwhites in the United States by the year 2000, approximately 14 pe of the population, and that by the year 2050 the proportion will rea percent. "The magnitude of the explosive growth of the Negro populai writes Mauser, "will undoubtedly make the problems of intergroup rel; iwnn mrm> flilTir.nli in thfi mmine vears." This exolosive arowth, he vsubstantial literature on differential fertility rates, less has been written on its social and political consequences.ion, for example, as a result of the dense concentration of automobiles. The cconomies-of-scale argument, therefore, cuts both ways. less important.